The development of the Biodiversity Exploratories Information System (here BExIS1) started more than 10 years ago and since then has been functioning as the data management platform and information system for the SPP 1374 “Biodiversitäts-Exploratorien” (BE). Since then, more than 1,000 datasets with a total of more than 20,000 variables and several million data rows were uploaded to the system. A dataset consists of metadata, a data structure, and the research data itself. Besides the storage of tabular data, it is also possible to upload unstructured data (files) to the system. Stored data is subject to common operations like updating, editing, and deletion. These actions led to various changes inside the datasets, which are reflected as versions or archived data. Of course, a lot of additional information to run such a system is stored. This mostly concerns authorization and authentication, but also plenty of personal information is included. Migrating data from one system to another is always a major and sometimes thrilling task. Data needs to be transferred without alterations. BEXIS2 uses a different schema to store and handle its data. Furthermore, some functionality is implemented differently from BExIS1. Examples include the concept of variables or the user management. These changes need to be considered during data migration and the transferred data needs to be adjusted to adhere to changed model. We implemented a system to transfer data from a BExIS1 instance to a BEXIS2 instance. BExIS1 data is accessed directly or by using BExIS1 functionalities. The data is then stored in BEXIS2 by making use of BEXIS2 API calls and by using auxiliary information. The main auxiliary source is an instance specific mapping of BExIS1 variables to the different BEXIS2 variable concept. We show our implementation of the system to migrate a production level Bexis1 instance into a newly set up Bexis2 instance. We show steps necessary and obstacles encountered together with our implemented solutions. We intend to make our implementation available to other BExIS1 instance users to facilitate and ease the migration to the new BEXIS2 system.